jim mcmahon just came out and said he suffers from dementia, so there is a fear. >> if you're going to stop football, you better stop hockey. >> reporter: symptoms are often subtle and easily missed. among children and adolescents, emergency room visits for sports-related brain injuries, including concussions, have gone up 60% in ten years. ask for boys, the rates are highest in football. >> from the nfl all wait down to pop warner youth football, unprecedented steps have been taken the last several years to make the game safer. >> reporter: more than half of the states in america, including new hampshire, have concussion laws to protect student athletes. at eastern tech in maryland, players take brain function tests to determine if and when they can play after an injury. >> it will tell me how severe my injury is, it will tell me how long i have to get back. >> reporter: banning football altogether may be extreme, but butler's proposal has triggered a passionate debate, forcing the country to take a different look at one of its most cherished pastimes. >>> up next on nightly news, the